新型粘弹性表面活性自转向酸的研制及性能评价

Performance appraisal of a new self-diverting acid with viscoelasticity and surface activity

在酸化或酸压施工中,由于酸液的滤失和酸岩反应速度过快,导致活性酸液的穿透距离有限或酸液因不能分流转向而进入高渗透带,从而降低酸化或酸压施工的效果,为了解决上述问题而研制了交联酸、温控变粘酸等多种高分子类型酸液体系,但却容易对油藏造成二次伤害。为此,在室内合成了一种粘弹性表面活性剂SL,利用该表面活性剂配制了新型的粘弹性表面活性自转向酸VDA-SL,并对其性能进行了评价。室内实验结果表明,当酸液质量分数为25%左右时,VDA-SL粘弹性表面活性自转向酸的粘度为20mPa.s左右,当酸液质量分数从21%降低到10%时,粘度出现变化。其变粘特性及机理与文献报导的高分子类变粘酸明显不同,随酸液的消耗,其粘度约在酸液剩余质量分数为20%处开始增大,当酸液质量分数降低到15%左右时粘度出现最大值,可以达到650mPa.s。

During acidizing and acid-frac process, filtration of acidizing fluid and rapid acid-rock reaction speed result in limited penetrating depth of active acidizing fluid or acidizing fluid entering into high permeability zones for not being able to bridge and divert. Then the effect of the acidizing and acid-frac process turns poorer. Many acidizing fluid systems with high molecule are developed including crosslink acid, temperature-control and viscosity-change acid and so on to solve the above problems, but it will bring secondary damage to oil reservoir easily. Therefore a new self-diverting acid VDA-SL with viscoelasticity and surface activity is prepared based on the synthetic viscoelastic surfactant SL. And the performance of VDA-SL is evaluated. The viscosifying mechanism of VDA-SL is completely different from that of the high-molecule acid; the viscocity of VDA-SL is a-bout 20mPa · s when the mass fraction of the acidizing fluid is a-bout 25% ; and it varies when the mass fraction reduces from 21% to 10%. The property and mechanism for its viscosity change are obviously different from those for self-diverting acid system reported in the references. Along with the consumption of the acidizing fluid, its viscosity begins to increase at 20% of the mass fraction of the acidizing fluid. Maximum viscosity will appear when the mass fraction reduced at 15% , it will be up to 650mPa · s.